Derwood



UNIT D STATES PATENT OFFICE.

GEORGE B. UNDERVOOD, OF TORONTO, ONTARIO, CANADA.

LOCK.

SPECIFICATION forming part of Letters Patent No. 349,017, dated September 14, 1886. Application filed April 12, 1886. Serial No. 198,589. (Modeh) To all whom it may concern.-

Be it known that I, GEORGE BRowN UN- DERWOOD, of the city of Toronto, in the Province of Ontario, in the Dominion of Canada, have invented certain new and useful Improvements in Door-Locks; and I do hereby declare that the-following is a full, clear, and exact description of the same.

My invention hasfor its object to accelerate the movement of gravity-tumblers by gravitating levers.

My invention consists of a lock-case having a post passing through a slot in abolt providod with a stud, gravitating tumblers hung on said post and notched to engage with the stud of the bolt, and gravitating levers to depress the tumblers ai'ter being raised by the key in shooting the bolt.

Figure 1 is a plan view of the interior of my improved lock. Fig. 2 is a section of the lock on line :0 m, Fig. 1. Fig. 3 is a section of thelock on line z 2, Fig. 1. Fig. 4 is a plan of the sliding bolt removed from the case, and Fig. 5 is aplan of the key.

A is the lock-case, both sides alike, whereby the lock can be reversed to suit doors open ing either to the right or left hand.

B are holes for the screws attaching the lock to the door.

C is a post having at top a hole to receive a screw, which secures the cover D in place, and E F G are posts integral with the lockcase.

H is the locking-bolt, sliding through an opening in the edge of the case, and said bolt is provided with parallel slots, E F, to receive, respectively; the posts E F, the post E supporting the bolt to slide horizontally in the case, and the round post F entering a hole in the tumblers J, near'one end. The tumblers, near the opposite end, are provided with a longitudinal slot, J, T-shaped at both ends, to receive a stud, H, projecting from the locking-bolt, which is cut away on either side of its center for a portion of its length,

to allow the tumblers to be placed in the recess. The tumblers are pivotally hung on post F, and the notches in slot J engage with stud H of the bolt; hence said bolt cannot be moved except by entering a key through the key-hole K, to lift the tumblers out of contact with the stud. The bolt may then be simultaneously slid by turning the key.

L are one or more gravitating levers, preferably corresponding in number to the num ber of tumblers, and said levers pivot on post G, and are provided with a downward projection, L, to bear against the edge of the tumblers and force the tumblers down after being raised by the key.

The gravitating levers and the tumblers are pivoted to the lock case in such manner that the free end of the levers will beabove the pivoted end of the tumblers and the free end of the tumblers below the pivoted end of the levers, thus causing a co-action of the parts, whereby greater resistance will be of-' fered to the key in turning to shoot the bolt than would be the case were both the levers and the tumblers pivoted at the same end.

M is a projection on a rock-shaft, M, journaled through the casing A, and said shaft has at both ends a hole to receive a key, 0,

for rocking the shaft, to bring the projection M against the gravitating levers L, whereby the tumblers and bolt cannot be moved by the aid of a key until the shaft is reversely rockedto rest the projection against :1 lug, N, integral with the lockcase.

In the better class of my improved lock the bolt is thinned from both sides, as shown in Figs. 2 and 3, to allow tumblers to be placed flatwise against opposite sides of the bolt; but in the cheaper locks the bolt may be thinned only on one side and the tumblers placed at that side.

The slots J in the tumblers are T-shaped at both ends, to provide greater security, should the tumblers be overlifted by an improper key, in which case the lower .notch would be brought in contact with the stud H, and prevent thekey being turned to slide the bolt; but, if desired, the slots may be L-shaped on the top side only.

I am aware that springs have been applied to looks to depress the tumblers and oiter increased resistance to the turning of the key; but springs are liable to break and get out of order. My gravitating levers are not subject to such contingencies, and have better efficicncy, and are not liable to derangement.

ICG

claim as new, and desire to secure by Letters gravitating levers L, oppositely pivoted, IO Patent, iswhereby the pivoted end of the levers will be 1. The gravitating levers L, pivoted to the above the free end of the tumblers and the lock-case, in combination with the tumblers J free end of the levers be above the pivoted 5 and bolt H, to give increased resistance to the end of the tumblers, as set forth.

key, as set forth. G. B. UN DEliW 001).

2. The combination, with the lock-case A, Vitnesses: having posts E F G, and bolt H, having slots JOHN WILLIAMsON,

E F, and stud H, of the tumblers J and F. M. MoRsoN. 

